1. Field of the Invention
The present invention relates to an electronic cassette and an electronic cassette apparatus for receiving radiation passed through a subject and detecting a radiation image.
2. Description Related to the Prior Art
An electronic cassette is known as a portable X-ray image detector for detecting an X-ray image which represents graphical information on a subject on the basis of radioactive rays, e.g. X-rays, that have penetrated the subject (refer to Japanese Patent Laid-open Publication No. 2012-088312, for example). The electronic cassette consists of a flat portable housing and a sensor panel, also called a flat panel detector (FPD), which is contained in the housing and is capable of outputting data of an X-ray image as digital dat. The sensor panel is provided with a rectangular imaging area which has, for example, a short side and a long side.
The electronic cassette can be used, for example, for round-visit radiography that is performed in a medical ward to take images from a patient who cannot come to an imaging room. In this case, the electronic cassette is carried into the medical ward along with a round-visit vehicle that is an automobile wagon having an X-ray generator boarded thereon. When making a round-visit radiography, a console equipped with an image display is also carried about in addition to the round-visit vehicle and the electronic cassette. The electronic cassette has a function to transmit X-ray images so that X-ray images can be checked on the carried console in the medical ward or the like by transmitting data of the X-ray images to the console immediately after the radiography. Furthermore, the X-ray images may be displayed on an image viewer terminal so that a doctor who has ordered the radiography can serve the X-ray images for diagnosis.
On the image display device of the console or that of the image viewer terminal, the display orientation of each X-ray image is determined with reference to an origin point of the read X-ray image in accordance with the initial default setup. The origin point of the X-ray image coincides with an origin point of an imaging area on the sensor panel of the electronic cassette. The electronic cassette may be used for imagining, for example, in a vertically-long position where the short sides of the rectangular imaging area become the head and bottom of the image, or in a horizontally-long position where the long sides of the imaging area become the head and bottom of the image. On the round-visit radiography, the vertically-long position and the horizontally-long position are selectively used depending upon the situation for imaging such as limited space in the medical ward.
Thus, the imaging position of the electronic cassette varies depending upon the situation. As a result, there may be cases where the subject of the X-ray image is oriented sideways on the image display device when displayed in accordance with the initial setting. In these cases, the radiologist or doctor should change the display orientation of the X-ray image on the image display device by turning the X-ray image through a necessary angle to adjust the subject to the proper orientation.
In order to adjust the image display orientation automatically, Japanese Patent Laid-open Publication No. 2012-088312 discloses an electronic cassette, of which the housing having a rectangular top planar shape is provided with a couple of cable connectors disposed respectively on a short side surface and a long side surface of the housing, these side surfaces being orthogonal to each other. Depending upon which of these cable connectors is connected to cables that transmit X-ray images or supply power to the electronic cassette, the head and bottom of the X-ray image are determined to be short sides or long sides. In the electronic cassette described in the above patent document, for instance, when the cable is connected to the cable connector on the short side, the short side having the cable connector is determined to correspond to the bottom margin of the X-ray image, whereas when the cable is connected to the cable connector on the long side, the long side having the cable connector is determined to correspond to the bottom margin of the X-ray image. Information on the head and bottom of the X-ray image is transmitted to the image display device along with the X-ray image. The image display device determines the head and bottom of the X-ray image on the basis of the received information on the head and bottom, to determine the image display orientation.
However, in some medical fields, like in the round-visit radiography where the electronic cassette should be taken out of the imaging room, there is a need for operating the electronic cassette without carrying a console in order to reduce the number of devices to be carried about. Because the round-visit vehicle is used in the medical ward, cables for the electronic cassette can bother the operation, and therefore wireless communication is desirable in many cases. Meanwhile, the medical ward may be under such circumstances that do not permit wireless communication because there are medical devices that can be affected by electromagnetic waves or wireless communication facilities are not established. In these fields where the use of cables is undesirable, but the wireless communication is not available, the operation without carrying the console is desirable.
The method disclosed in the above patent document, determining the head and bottom of the X-ray image by the choice between the cable connectors, is not applicable to the operation without the cable. However, the cable wiring is actually bothersome and greatly limits the positioning flexibility of the electronic cassette. Furthermore, there may be cases where the cable wiring direction is limited by the positioning condition of the electronic cassette and the spatial condition of the imaging location so that the cable cannot be connected to the desired cable connector to select for the desired display orientation, or even worse, the cable cannot be connected to the electronic cassette. In those cases, it is impossible to select or change the head and bottom of the X-ray image.